Plant Kingdom Class 11 Notes CBSE Biology Chapter 3 (Free PDF Download)

Section–A (1 Mark Questions)

1. What is a pyrenoid body?

Ans. In Chlorophyceae (green algae), most of the members have one or more storage bodies called pyrenoids located in the chloroplasts. The pyrenoid body contains a core that is proteinaceous in nature and is surrounded by a sheath of starch.

2. Which group of plants is regarded as the first terrestrial plants? Why?

Ans. Pteridophytes plants are regarded as the first terrestrial plants. This is because the pteridophytes are more adapted to suit the ‘harsh nature of the environment’ which was present at the time.

3. Define antherozoid and antheridium.

Ans. The sex organs in bryophytes are multicellular. The male sex organ is called antheridium. They produce biflagellate antherozoids.

4. What is the economic importance of Sphagnum?

Ans. Some species of Sphagnum provide peat that has long been used as fuel and manure. Dry Sphagnum is used as packing material for trans-shipment of living material because of its water holding capacity. 

5. Name the reserve food material in the following:

(a) Brown Algae

(b) Red Algae

Ans. (a) The reserve food of brown algae is laminarin. 

(b) In red algae, the food is stored as floridean starch.

Section–B (2 Mark Questions)

6. (i) Which tree is regarded as one of the tallest tree species?

(ii) Define zoospores.

Ans. (i) The giant redwood tree Sequoia is a gymnosperm that is one of the tallest tree species.

(ii) A zoospore is a motile asexual spore that uses a flagellum for locomotion. On germination, they give rise to new plants.

7. List four classes of pteridophytes with one example each.

Ans. The four classes of pteridophytes are: 

a. Psilopsida- e.g., Psilotum

b. Lycopsida- e.g., Selaginella, Lycopodium

c. Sphenopsida- e.g., Equisetum

d. Pteropsida- e.g., Dryopteris, Pteris, Adiantum.

8. Define homosporous and heterosporous.

Ans. Homosporous- In the majority of the pteridophytes, all the spores are of similar kinds; such plants are called homosporous, e.g., Equisetum, Lycopodium.

Heterosporous- Some genera like Selaginella and Salvinia produce two kinds of spores- macro (large) and micro (small) spores. They are known as heterosporous.

9. (a) Name the class of algae in which motile cells are absent.

(b) Define sporophyll and sporophyte.

Ans. (a) Red algae (Rhodophyceae) are characterized by the absence of any motile gametes or spores.

(b) Sporophyll- The sporophytes bear sporangia that are subtended by leaf-like appendages called sporophylls. 

Sporophyte- Zygotes do not undergo reduction division immediately. They produce a multicellular body called a sporophyte.

10. How is the leafy stage formed in mosses? How is it different from protonema?

Ans. The leafy stage in some mosses develops from a lateral bud in the secondary protonema. It is a small leafy structure consisting of rhizoids, leaves, and stems. They consist of upright, slender axes bearing spirally arranged leaves. It bears the sex organs, antheridia and archegonia. Whereas, Protonema stage of mosses directly develops from the haploid spores.  It is a creeping, green, branched, and frequently filamentous stage.

11. Define:

(a) Male strobili

(b) Female strobili

Ans. (a) The strobili bearing microsporophylls and microsporangia are called microsporangiate or male strobili.

(b) The cones bearing megasporophylls with ovules or megasporangia are called macrosporangiate or female strobili.

Access Class 11 Biology Chapter 3 – Plant Kingdom

Whittaker classified the whole living organism into five kingdoms based on the complexity of cell structure  (Prokaryotic and Eukaryotic), the complexity of the body (unicellular and multicellular), and mode of nutrition  (autotrophs and heterotrophs). 

Classification of the Plant Kingdom:  

All the classification systems, starting from that of Aristotle to the 20thcentury, can be divided into three types: 

1. Artificial System: In this system, the classification is based on few morphological characters. 

Theophrastus, Pliny, and Linnaeus used an artificial system of classification.                              

2. Natural System: In this system, the classification is based on all the important related characters. Both external and internal. Bentham and hooker, Adanson, Candolle used a natural system of classification. 

3. Phylogenetic System: Classification based on the evolutionary relationship of plants. The use of phylogeny for classification was done by Eichler, Blessy, Whittaker, Engler, and Prantl, Hutchinson. 

Numerical Taxonomy: Taxonomy based on statistical methods with equal importance using computers. 

Cytotaxonomy: Taxonomy that is based on cytology or structure of the cell (chromosome number, shape, behaviour, etc). 

Chemotaxonomy: Taxonomy based on chemical constituents of plants (nature of the protein, DNA sequence, taste, smell, etc). 

Eichler Classification: The classification of Plant kingdom depending on flowering. Divided into two-Cryptogamae (non-flowering, seedless plants) and Phanerogamae (flowering, seed-bearing plants). 

Based on the Plant Body Cryptogamae is divided into Thallophyta, Bryophyta, and Pteridophyta. 

• Thallophyta: The plant body is thallus-like (undifferentiated plant body).

• Bryophyta: plant body with a root-like structure, stem-like structure, vascular tissues are absent). 

• Pteridophyta: The plant body is differentiated into true root, stem, and leaves. Vascular tissues are present in so-called vascular cryptogams.

Thallophytes Again Divided Into:

• Algae (pigmented thallophytes)  

• Fungi (non-pigmented thallophytes)  

• Lichens: Symbiotic association between algae and fungi. 

Phanerogamae is Divided Into Two:

• Gymnosperms (naked seed plants) and 

• Angiosperma (covered seeded plants) 

Angiosperms Are Again Divided Into Two:

• Monocots (bearing single cotyledon, fibrous root system, and parallel venation)  

• Dicots (have two cotyledons, taproot system, and reticulate venation). 

Due to the Presence of Vascular Tissue, the Pteridophytes, Gymnosperms, and Angiosperms are called Tracheophytes.

Due to the Presence of Embryos the Bryophyta, Pteridophyta, Gymnosperms, and Angiosperms are called Embryophyta.

3.1 ALGAE: 

• Phycology: Branch of Biology that deals with the study of algae 

Phycos=seaweed 

Logos=study 

• Fritch –Father of phycology. 

• M.O.P.Iyengar is the father of Indian phycology. 

Algal members are pigmented thallophytes. 

Habitat: 

Hydrophytes: Water is their habitat. In aquatic habitat-

• Freshwater (Spirogyra) and marine    (Sargassum). 

• Floating- Chlamydomonas, Spirogyra 

• Benthophytes - These plants remain attached to the bottom of their habitat. Example Chara (stoneworts)  

• Xerophytes: Their habitat is desert. 

• Mesophytes- They grow in medium habitats. 

• Epiphytes- They grow on plant body (Cladophora) 

• Epizoic-growing on the animal body (Trichophillus) 

• Lithophytes- They grow on rocks. 

• Halophytes- They grow in salty areas. 

• Moist soil-terrestrials (Fritschiella). 

Plant Body: 

• The vegetative plant body of algae is a haploid gametophyte. 

• They may be unicellular, flagellated (Chlamydomonas), or non-flagellated (Chlorella) 

Multicellular: 

a) Coenobium-It is a colony with a fixed number of cells and also the division of labor is fixed. Eg: Volvox 

b) Aggregation-indefinite colony. Eg: Tetraspora 

c) Filamentous-unbranched.Eg: Ulothrix 

d) Filamentous branches. Eg: Cladophora 

e) Siphonous- multinucleate. Eg: Vaucheria 

f) Parenchymatous. Eg: Ulva the,

g) Branched like higher plants. Eg: Sargassum, Chara 

Nutrition: 

• Autotrophs - Photosynthetic (most of them) 

• Parasitic forms (rare). Eg: Cephaleuros. 

Pigments: 

• Chlorophyll- a, b, c, d. 

• Carotenoids- carotene and xanthophyll-fucoxanthin are dominating pigments in brown algae.

• Phycobillins- phycocyanin and phycoerythrin. 

Reproduction: 

• Vegetative reproduction- Reproduction Using the Vegetative Parts. 

Different Types are: 

1. Fission 

2. Fragmentation 

3. Budding 

4. Tubers 

5. Gemmae. 

• Asexual Reproduction-Without the Fusion of Gametes. 

Mainly by: 

1. Zoospores within sporangia 

2. Aplanospores 

3. Akinete 

4. Hypnospores 

5. Endospore 

6. Exospore  

7. Monospore 

8. Auxospore. 

Palmella Stage-In this stage of asexual reproduction the spores become colonial and appear like the algae named Palmella. Eg: Ulothrix, Chlamydomonas. 

• Sexual Reproduction: 

Homogametes-similar gametes 

Heterogametes-dissimilar gametes 

1. Isogamy: fusion of morphologically and physiologically similar gametes.  Isogamy- flagellated (Chlamydomonas ) and non flagellated (Spirogyra). 

2. Anisogamy: fusion of morphologically or physiologically dissimilar gametes.  Morphologically dissimilar gametes’ fusion occurs in Chlamydomonas. Physiologically dissimilar gametes’ fusion occurs in  Spirogyra. 

3. Oogamy- It is the fusion of morphologically and physiologically dissimilar gametes that are small motile male gamete and large nonmotile female gamete. 

Eg: Fucus, Volvox. 

• Exceptional Cases:  

Unicellular antheridium and oogonium.Eg: Oedogonium. 

• Special Reproductive Structures: 

Conceptacles –Eg: Sargassum 

Globule (antheridium) and nucule (oogonium) Eg: Chara 

• A special type of sexual reproduction called conjugation is found in spirogyra. 

The life cycle exhibits two phases-haploid and diploid and some of them exhibit alternation of generation. The diploid phase is alternated with the haploid phase. 

Classification of Algae: 

They are classified into three- 

• Chlorophyceae 

• Phaeophyceae  

• Rhodophyceae. 

3.1.1 Chlorophyceae: 

In Chlorophyceae, the plant body is unicellular as in Chlamydomonas or colonial as in Volvox or filamentous as in Spirogyra. 

• Different Shapes for the Chloroplast- 

1. Ribbon shaped and spiral in Spirogyra

2. Girdle shaped in Ulothrix 

3. Cup shaped chloroplast in Chlamydomonas 

4. Star-shaped in Zygnema 

5. Disc-shaped in Caulerpa 

6. Reticulate in Oedogonium. 

• Photosynthetic pigments are chlorophyll a and b. 

• Food is stored in the form of starch and some are stored in the form of oil droplets. 

• Pyrenoids are present, which are the storage bodies. 

• The inner layer of the cell wall is made up of cellulose and the outer layer is made up of pectose. 

• The members reproduce:  

1. vegetatively by fragmentation 

2. Asexually by flagellated zoospores  

3. Sexually by isogamy, anisogamy, and oogamy. 

• Common Chlorophyceae members are:  

Chlamydomonas, Chlorella, Volvox, Ulothrix, Ulva, Caulerpa, Chara, Acetabularia etc. 

3.1.2 Brown Algae or Phaeophyceae:

• They are marine. 

• Simple branched and filamentous as in Ectocarpus, or flat ribbon-shaped in Sargassum, Laminaria, Fucus, etc. 

• The giant brown algae Kelps are the largest sea plants, some are free-floating as in Sargassum and some are epiphytes on other plants like Ectocarpus. 

• The Plant Body has Three Parts- 

1. Fixing structures called a holdfast 

2. The stalk-like structure called a stipe  

3. The leaf-like structure is called a frond. 

• Pigments present in brown algae are chlorophyll a, c, carotenoids, and xanthophylls. 

• Food is stored as laminarin and mannitol, which are complex carbohydrates.

• The cell wall is made up of cellulose and it remains covered by a gelatinous coating algin on the outer part. Algin is a phycocolloid (hydrocolloid) that helps the thallus stay moist during low tide.

• The cell consists of cell organelles in which vacuole is placed which helps the thallus in floating. 

• Vegetative reproduction occurs by the process of Fragmentation 

• Asexual reproduction occurs by biflagellated zoospores which are pear in shape with two flagella attached laterally. 

• Sexual reproduction occurs by the process of fusion of gametes. It includes:

1. Isogamy, 

2. Anisogamy  

3. Oogamy. 

• Gametes are pear-shaped having two laterally attached flagella. 

• The most common brown algae are Ectocarpus, Laminaria, Dictyota, Sargassum, and Fucus. 

3.1.3 Rhodophyceae (Red Algae): 

• Commonly called red algae. 

• They are mostly marine and rarely freshwater. Eg: Betrachospermum. 

• They occur in the well-lighted region and also in the depths of oceans. 

• The thallus is multicellular.

• Pigments present in red algae are chlorophyll a, d and phycoerythrin.

• Due to the presence of red pigment r-phycoerythrin, the color of algae is red. 

• Food is stored in the form of floridean starch which is similar in structure to amylopectin and glycogen. 

• Vegetative reproduction by fragmentation 

• Asexual reproduction by nonmotile spores 

• Sexual reproduction by the process of Oogamy and bears complex post-fertilization developments. 

• The commonly found red algae are Polysiphonia, Porphyra, Gracilaria, Gelidium, Betrachospermum, etc.

• Economic Importance of Algae:
  

• In the food chain algae are the primary producers. The basis of the food cycles of all aquatic animals is formed by the algae. 

• On earth, half of the total carbon dioxide fixation is carried out by algae through the process of photosynthesis. 

• In the purification of air and water it plays a very important role. 

• Some algae are edible. Eg- Chlorella, Laminaria, Porphyra, Sargassum, Ulva, Spirulina.   

• Some algae are used as fodder. Eg; Laminaria, Sargassum, Fucus. 

• It also acts as a food supplement for space travelers. Eg. Chlorella, Spirulina. 

• From red algae, algin and carrageenan are obtained which are water-holding substances or hydrocolloids. 

• Agar is obtained by Gelidium and Gracilaria. It is used to grow microorganisms. 

• Used in the preparation of culture medium in tissue culture experiments. 

• It has medicinal values as antibiotics are prepared from them. 

• Eg: Chlorella, Polysiphonia. 

• Also used as a source of minerals- Polysiphonia, Laminaria 

• Has importance in biological research: Chlorella, Acetabularia. 

• Common Names of Algae:

• Water silk-Spirogyra 

• Sea lettuce- Ulva 

• Umbrella plant-Acetabularia ( Largest unicellular algae)

3.2 Bryophytes:  

• Simplest non-vascular land plants with undifferentiated plant bodies. 

• Bryology-Study of Bryophytes 

• Hedwig- Father of bryology 

• S.R.Kashyap-Father of Indian bryology 

• The bryophytes are also called the amphibians of the plant kingdom due to their unique characteristics. 

• Bryophytes grow in dense patches on moist shady places like walls, damp soil, tree trunks, etc. 

• Features:  

• Habitat: Mainly terrestrial but some are aquatic. E.g- Riccia fluitans 

• Epiphyllous –E.g: Radula 

• Plant body-Thallus and Prostate. Eg: Riccia, Anthoceros, Marchantia or Erect. Eg- Moss. 

• Root-like structures called rhizoids help in fixing them in the soil. 

• The body of the plant is differentiated into stem-like and leaf-like structures. 

• Vascular tissues are absent. 

• Vegetative reproduction occurs by fragmentation, budding, tubers, etc. 

• Asexual reproduction occurs by Gemmae- asexual buds in liverworts. 

• Sexual reproduction occurs. The vegetative plant body acts as the gametophyte and all the members are homosporous. 

• Multicellular sex organs are present that are found in clusters. 

• The club-shaped antheridium is the male reproductive organ and it produces biflagellate antherozoids which are motile too. 

• The flask-shaped archegonium is the female reproductive organ and it produces the egg. 

• To form the zygote the antherozoid fuses with the egg. 

• The sporophyte is not free-living and it derives nutrients from the photosynthetic gametophyte. 

• After meiosis, the haploid spores are formed in the sporophyte and the spore germinates to form the gametophyte.

• Alternation of generation is present where the haploid phase alters with the diploid phase. 

• Both the phases are multicellular.

• The gametophyte is the dominant photosynthetic free-living stage. 

• The sporophyte is short-lived and it highly depends on the gametophyte.

• For fertilization, water is very much essential. 

• Classification of Bryophytes: It has three classes: 

1. Hapticospida (liverworts) 

2. Anthocerotopsida (Hornworts) 

3. Bryopsida. (Moss) 

3.2.1 Hepaticopsida or Liverworts: 

• The plant body is photosynthetic, flat, and have dorsiventral thallus .E.g.: Riccia, Marchantia 

• The rhizoids are present that help the thallus to remain attached to the soil. 

• Vegetative reproduction is by the process of fragmentation. E.g.: Riccia, Marchantia 

• In some bryophytes, the reproduction occurs by the gemmae formation. E.g.: Marchantia 

• Gemmae develop into small receptacles which are called gemma cups and are green multicellular, asexual buds. To form the new thallus the gemma gets detached from the parent body and germinates. 

• Sexual reproduction: Sex organs present are antheridia and archegonia. They are formed either on the same thalli or different thalli. 

• The sporophyte can be differentiated into three parts-foot, seta, and capsule. Meiosis takes place in the capsule to form the haploid spores which germinate into free-living thalloid gametophytes. 

• Anthoceropsida or Hornworts: E.g.: Anthoceros, Notothylas. 

• Anthoceros is commonly known as hornworts 

• They contain pyrenoids. 

• Symbiotic nitrogen fixation is present. 

3.2.2 Bryopsida (Moss): 

• They are higher bryophytes 

• The gametophyte consists of two stages-protonema and the leafy stage. 

• Protonema is green filamentous, branched, creeping structures that directly develop from the spore on germination and they also bear branched rhizoids and lateral buds. 

• The leafy stage is developed as a lateral bud from the secondary protonema. 

• The plant body consists of root-like, stem-like, and leaf-like structures. Eg: Funaria. 

• Rhizoids are multicellular and branched also. 

• The leafy stages bear the sex organs. 

• Vegetative reproduction occurs by the process of fragmentation  and budding in the secondary protonema. 

• In mosses the spore dispersal mechanism is elaborate. 

Eg: Funaria, Polytrichum, Sphagnum etc. 

• Economic Importance  

• They are used as food by herbaceous animals. 

• Sphagnum (Moss) occurs in the form of peat and is used as fuel. 

• Because of its water holding capacity, the mosses are also used for the trans-shipment of living material 

• Moses also prevents soil erosion. 

• They are the first colonizers on barren rocks along with lichens. 

• For the growth of the higher plants or succession, they decompose rocks for making substrate. 

3.3 Pteridophytes: 

• They are the first terrestrial plant to bear vascular tissue such as xylem and phloem. So they are also called vascular cryptogams.

• Commonly known as a botanical snake. 

• The plant body is differentiated into true root, stem, wind-needle-like, and leaf. 

• The plant body is the sporophytic generation. 

• The stem is rhizomatous and they regenerate when aerial parts are destroyed. 

• Leaves may be small known as microphyll as in Selaginella or large known as macrophyll as in ferns.

• Coiling of Young Leaves - Circinate vernation is Seen in Pteridophytes. 

• Two types of leaves are found vegetative and fertile. 

• Fertile leaves are spore-bearing leaves called sporophylls. 

• Spores are formed inside the sporangia. In Sporangia, the spore mother cells give rise to spores after the process of meiosis. 

• Spores germinate to form a haploid gametophyte, photosynthetic heart-shaped multicellular structure called prothallus which bears antheridia and archegonia. 

• For growth, prothallus requires cool, damp, and shady areas whereas water is essential for fertilization. 

• The antheridia bear antherozoids and archegonia bear the egg cell respectively which on fertilization form zygote which on germination forms the sporophyte. 

• Most of the pteridophytes form similar kinds of spores, therefore, called homosporous. Two kinds of spores, macro or large spores and small or microspores, which are heterosporous are produced by the genera like Selaginella and Salvinia. Male and female gametophytes are produced when microspores and microspores germinate. 

• In heterosporous conditions the female gametophyte is not free-living, it is retained in the parent sporophyte till the beginning of the embryo development. 

• Seed-bearing plants evolved from heterosporous pteridophytes. 

• Pteridophytes are further classified into four classes:  

1. Psilopsida (Psilotum) 

2. Lycopsida (Selaginella) 

3. Sphenopsida (Equisetum ) 

4. Pteropsida (Pteris). 

• Economic Importance:  

• Some members are Medicinal- Dryopteris 

• Helps in Soil binding 

• Used as Ornamental plants 

• Edible plants- Marcelia 

• Used in Crop rotation- Azolla 

• Helps in Symbiotic nitrogen fixation. 

• Play an important role in the succession of plants on bare rocks or soil.

• Sphagnum is used to keep seedlings in gardens and also in keeping cut plant parts moist during transportation and propagation. 

• Common Names: 

• Creeping pine/Club moss- Lycopodium 

• Spike moss(Resurrection plant- Selaginella 

• Water fern- Azolla (smallest pteridophyte) 

• Walking fern (Maiden hall fern)- Adiantum 

• Adder’s tongue fern- Ophioglossum 

• Fossil pteridophyte- Cooksonia 

• Leafless Pteridophyte- Psilotum 

• Horsetail- Equisetum 

3.4 Gymnosperms: 

• Have naked seeds because the ovules are not enclosed within or by any ovary wall and they remain exposed (no fruit covering). Flowerless seed-bearing plants. 

• Ovules are also not enclosed by the wall of the ovary. 

• Dominant plants during the Jurassic period. 

• Gymnosperm includes trees which are medium-sized  or taller and also the shrubs. 

• Taproot system is generally present. They are also associated with mycorrhiza, which is the association between fungus and roots of higher plants. Eg: Pinus. Coralloid roots bearing nitrogen-fixing bacteria as in Cycas. 

• The stem is branched (Pinus), or unbranched (Cycas). 

• Leaves are adapted for extreme temperature, humidity, and wind-needle-like leaves with thick cuticles, sunken stomata. Eg: Pinus. 

• Leaves may be simple or compound. 

• The stem is unbranched as in Cycas 

• Branched in Pinus and Cedrus 

• Well-developed vascular system –xylem without vessels. 

• Reproductions: 

• Sporophylls are aggregated to form stromboli or cones. They are generally monosporangiate or of two types male and female cones. 

• Male cones are short-lived whereas female cones are long-lived. 

• Male strobili or male cone – microsporophylls which bear microsporangia having microspores which develop into reduced gametophyte called a pollen grain. 

• Female cone or female strobili –megasporophylls which bear megasporangium having megaspores which are enclosed within the megasporangium (Nucellus).  

• One megaspore develops into a female gametophyte bearing two or more archeonies. Pollen grains are carried by the wind and they reach the ovules. 

• They form a pollen tube that reaches the archegonia and releases male gametes into the ovule. Fusion of the gametes takes place and the zygote is formed which produces embryos. Ovules develop into seeds that are not covered. 

• The endosperms in gymnosperms are like, and a pre fertilization product and haploid in nature. 

• The dominant photosynthetic independent stage is the sporophyte. The gametophyte ranges from single to few celled but is not free living. 

• Classified Into Four Classes: 

1. Cycadopsida Eg: Cycas 

2. Coniferopsida eg: Pinus 

3. Gnetopsida: Eg: Gnetum. 

4. Gingopsida- Ginko 

• Economic Importance:  

• Timbers for furniture, Pulpwood, Pencil box, Musical instruments, etc. 

• Production of resins, Turpentine etc.-E.g.-Pinus 

• Edible seeds: Eg- Cycas, Pinus, Ginkgo. 

• Medicinal Eg: Ephedrine from Ephedra are used in treatment for respiratory problems

• Taxol – from Taxus species are extracted to freeze cancer cells. 

• Common Names: 

• Maidenhair tree- Ginkgo 

• Sago palm are called the Panda of the plant kingdom- Cycas 

• Largest gymnosperm- Sequoia 

• Smallest gymnosperm- Zamia 

• Gymnosperm with xylem vessels- Ephedra, Gnetum. 

3.5 Angiosperms: 

• Angiosperms are also known as flowering plants and they have covered seeds. 

• They are divided into two classes – 

• Dicotyledons (have two cotyledons)  

• Monocotyledons (have one cotyledon). 

• Smallest angiosperm: Wolfia (microscopic). 

• Large tree: Eucalyptus over 100 meters. 

• Reproductive organs are developed in flowers. 

• The Male sex organs present in a flower are called stamens or androecium. 

• It has filament and another. Anthers on meiosis produce pollen grains. Pollen grains have two male gametes. The female reproductive part in the flower is called the pistil or gynoecium. It has stigma, style, and Ovary 

• The ovary has one or many ovules in which the female gametophyte (embryo sac) develops by meiosis. 7 cells and 8 nuclei are present in the embryo sac. They are: 

• One (1) egg cell 

• Two (2) synergids 

• Three (3) antipodal  

• One (1) central cell having two polar nuclei. 

• The pollen grain is carried by various agents like wind, water, birds, insects, etc., and reaches the stigma. 

• Pollen grains produce a pollen tube that contains two male gametes and enters into the embryo sac. 

• One male gamete fuses with the egg cell to form a zygote and is called syngamy which develops into an embryo. 

• Other male gamete fuses with the secondary nucleus that is formed by fusion of two polar nuclei and produces triploid primary endosperm nucleus (PEN) and is called triple fusion. 

• PEN develops into an endosperm that nourishes the developing embryo. As two fertilizations, namely syngamy and triple fusion, occur inside the embryo sac simultaneously, it is called double fertilization. 

• The endosperm is triploid. 

• Ovules get to develop into seeds whereas ovaries into fruits. 

3.6 Alternation of Generation: 

There exists an alternation of a haploid gamete which is producing gametophytic and spore-producing sporophytic generation. 

Three types: 

1. Haplontic Life Cycle: In this type of lifecycle, the dominant, photosynthetic phase is a free-living gametophyte produced by haploid spores. The gametophyte produces gametes by the process of mitosis and the gametes fuse to form the zygote which represents the sporophytic generation. The zygote undergoes the process of meiosis to form haploid spores. Here the Gametophytic phase is dominant. e.g., Chlamydomonas. 

2. Diplontic Life Cycle: Here the diploid sporophyte is the photosynthetic independent phase of the plant which is dominant too. The gametophytic phase is represented by one to a few celled haploid gametophytes nourishes. Here the sporophytic phase is dominant. e.g., Angiosperms and Gymnosperms. 

3. Haplo-Diplontic Life Cycle: Both haploid and diploid phases are multicellular and mostly free-living in this type. Bryophytes and pteridophytes are examples.

Although haplontic life cycle has been shown by most algal genera  some of them are Ectocarpus, Polysiphonia, Kelps,  etc. But some also exhibit a haplo-diplontic life cycle. Fucus, a brown alga, exhibits a diplontic life cycle. 

Fast Track Revision: 

1. The Plant Kingdom Divided into two-Cryptogamae (non-flowering seedless plants) and Phanerogamae  (flowering, seed-bearing plants). 

2. Based on the plant body Cryptogamae is divided into Thallophyta, Bryophyta, and Pteridophyta. 

3. Thallophytes again divided into 

• Algae (pigmented thallophytes)  

• Fungi (non-pigmented thallophytes)  

• Lichens: Bears symbiotic association between algae and fungi. 

4. Phanerogamae is divided into two 

• Gymnosperms (naked seed plants) and 

• Angiosperma (covered seeded plants) 

5. Angiosperms are again divided into two 

• Monocots have a single cotyledon, fibrous root system, and parallel venation in leaves.  

• Dicots have two cotyledons, a taproot system, and reticulate venation in leaves. 

6. Algae are very simple, thalloid, autotrophic also, and mainly aquatic organisms. 

7. Algae are classified into three classes: Chlorophyceae, Phaeophyceae, and Rhodophyceae depending on the type of pigment possessed and the type of stored food. 

8. Vegetative reproduction by fragmentation, asexual reproduction by the formation of different types of spores, and sexually reproduced by the formation of gametes which show isogamy, anisogamy, and oogamy. 

9. Bryophytes are plants that can live in soil but for sexual reproduction, they are dependent on water. Their plant body is more differentiated as compared to the algae. 

10. Rhizoids have a thallus-like plant body, which is prostrate or erect, and have fixing structures. They bear root-like,  leaf-like, and stem-like structures. 

11. The bryophytes are divided into liverworts, hornworts, and mosses. 

12. Liverworts have a thalloid plant body and dorsiventral. 

13. Mosses bear spirally arranged leaves and have an upright and slender axis. 

14. The plant body is a gametophyte and after fusion of the gametes, the zygote produces a multicellular body called the sporophyte. 

15. In pteridophytes, the plant body is a sporophyte with root, stem, and leaves. 

16. The sporophyte in Pteridophyte bears sporangia which produce spores which on germination form gametophyte. 

17. In Pteridophyte the gametophyte possesses both male and female sex organs called antheridia and archegonia respectively. 

18. For fertilization water is essential.

19. The gymnosperms are the plants producing naked seeds and after fertilization, the seed remains exposed. 

20. Gymnosperms produce microsporophyll and megasporophyll. Microsporangia and Megasporangia are born on the sporophylls. 

21. Sporophylls-Microsporophyll and megasporophyll. 

22. The pollen tube made by the pollen grain releases the male gamete into the ovule. In the ovule, it fuses with the egg cell in archegonia. Following the process of fertilization, the zygote develops into an embryo and finally the ovules into seeds. 

23. In angiosperms, the male sex organs the stamen, and the female sex organ the pistil are present in a flower. 

24. The stamen consists of anther and filament. 

25. Pistil contains ovary, style, and stigma. 

26. The pollen grain produces two male gametes. One male gamete fuses with the egg and is called syngamy and forms a zygote which develops to form the embryo. 

27. The other male gamete fuses with the polar nuclei and is called triple fusion and forms the primary endosperm nucleus which develops to form the endosperm which nourishes the developing embryo. 

28. As two fertilizations are taking place inside the embryo sac simultaneously –syngamy and triple fusion, it is called double fertilization. 

29. Angiosperms are divided into two classes namely monocotyledons and dicotyledons. 

Biology Chapter 3 Class 11 Notes – Free PDF Download

Notes of Biology Class 11 Chapter 3 would help in preparing this subject for the CBSE Board examinations. If a student has more clarity on these topics, it becomes easier to obtain higher marks. Even though the chapter is fairly simple, the detailed information can get a little confusing for students. For clarity, a PDF of Chapter 3 Biology Class 11 Notes can be downloaded from Vedantu's official website. 

Biology Notes for Class 11 Chapter 3 Cover Some of the Topics 

Classification of Plants 

Classification of plants or its taxonomy primarily considers differentiation of plant body, tissues involved in the mechanism of transportation, and presence of seeds, among others. The divisions are –

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• Thallophyte: Includes microorganisms such as fungi, algae, and bacteria. In algae, the cell wall is composed of cellulose, and food is stored in the form of starch. 

• Bryophyta: These plants grow both on land and in water. Examples – Moss, Liver Warts etc. 

• Pteridophyte: Flowers and seeds are not present in these plants. Example – Ferns.

• Gymnosperm: The seeds remain uncoated, and there is no ovary. 

• Angiosperm: The seeds are coated and developed within an ovary. 

1. Monocot: In this type of angiosperms, only one cotyledon is present. Also, leaves are parallel-veined, and vascular bundles are scattered. The root system is adventitious. Examples – Wheat, Maize, Rice etc. 

2. Dicot: There are two seed leaves present in dicot angiosperms. Vascular bundles are in a ring and veins are branched. Also, tap roots are present. Examples – Potato, Pea, Banyan etc. 

Eichler’s Classification 

Eichler's classification laid down such a system that divides the plant kingdom into two types. The two divisions of cryptogamic and phanerogamic are discussed in Class 11 Biology Ch 3 Notes.

Cryptogamae includes seedless and flowerless plants. Those are mostly lower plants. Phanerogamae, on the other hand, are plants that bear seeds. These are higher plants where the body is differentiated into stem, roots, and leaves. 

Classification of Algae 

The classification of algae is clearly explained in Class 11 Bio Ch 3 Notes. Algae are divided into -

• Chlorophyceae: These are mostly green algae. The green colour is owing to the presence of chlorophyll a and b. Example – Spirogyra.

• Rhodophyceae: These algae have red pigment. The red pigment is r-phycoerythrin. Example - Gelidium.

• Phaeophyceae: These marine algae are predominantly brown in colour. The pigments are carotenoids and xanthophyll. Example – Sargassum.

If prepared well, chapter 3 can be quite scoring. Class 11 Biology Chapter 3 Notes mention all the necessary details. However, if there remains any doubt regarding the chapter, students may participate in online classes of Vedantu. To reach out to us,  you can also choose to download our app on your preferred device.

Importance of CBSE Class 11 Biology Chapter 3 Plant Kingdom Notes

The third chapter of CBSE Class 11 Biology is the Plant Kingdom. As the name suggests, we can clearly understand that this chapter explains the whole world of plants in a shorter version. Students will learn what flowering and non-flowering plants are in this chapter. They will also learn the different features of various types of plants elaborately and develop a strong conceptual foundation about the plant kingdom.

To make this chapter easier to understand and prepare, students use the notes designed by the experts. These notes comprise the simpler version of all the topics explained in this chapter. As these notes are designed based on the latest CBSE Class 11 Biology syllabus, it covers all the fundamental principles related to the world of plants. Hence, these notes will be the perfect study material for the students to carry on their preparation and revision before an exam.

Studying these notes will be easier due to their organised format. In fact, students will be able to focus on the prime concepts of this chapter and revise it faster. Hence, these notes are the part and parcel of the study and revision sessions of the students of Class 11.

Advantages of CBSE Class 11 Biology Chapter 3 Plant Kingdom Notes

• These notes have been compiled in a simpler and more concise version of the entire chapter. The explanation of the topics here is factually correct. You can use these notes for studying and preparing this chapter.

• Save your time by using these notes to revise these notes. There is no need to hover over the entire chapter when you can do it faster by referring to these notes.

• Focus on the simpler explanation of the notes and recall what you have studied perfectly during an exam. This is how you can score more in the exams.

• Keep these notes handy on your computer and use them to resolve doubts instantly.